Three-dimensional geohydrologic and geochemical framework analysesrequire reliable subsurface data. This includes collecting Geologic,Geophysical, Hydrologic, and Geochemical data. The Western RegionResearch Drilling Program (WRRDP) collects these data in all types of geologic environments using multiple drilling methods, geophysicallogging of holes, and installation of wells and other instruments.

Logging and ConstructionMud DrillingAir Drilling

Wireline Coring

Monitoring

Drilling MethodsDrilling MethodsUsed by the Western Region Research Drilling ProgramUsed by the Western Region Research Drilling Program

Steven CrawfordU.S. Geological SurveyWestern RegionHenderson, Nevada

Core barrel retrieved Barrel broken down Liner with core removed from barrel

Coring sample

Noimage

Scale incentimeters

205 feetScale: In feet

below landsurface

206 feet

207 feet

208 feet

209 feet

210 feet

Western Region Research Drilling Program drill rig

Wireline coring is the most efficient method for collecting cores. Cores collected using this method greatly enhance subsurface data. Using the wireline system, cores can be taken continuously, or the drill-ahead system can be used if cores are taken intermittently. The WRRDP drill rig is capable of continuous coring a hole, then switching over to traditional drill pipe to ream the hole for instrumentation.

Note: Spring retract allows core barrel to protrude beyond cutting bit in soft zones. This protects the core from mud or air invasion.

Latching up to core barrel

5-foot barrel attached to5-foot spring retract

Hoisting core barrel upto line up over wireline casing

Core barrel being tripped down hole

Extraction of liner containing core material

Proper handling and recording of core is critical prior to lab analysis.

Wireline Coring

Liner is cut and core is described

Foot interval samples show dramatic changes on small scale.

Measuring EC and Cl

Simple onsite measurementsplotting chloride profile

Cores can be immediately sealed airtight. Chemical and physical properties of the core material can then be analyzed in the lab.

Air-hammer drilling is used in hard rock and unconsolidated-unsaturated studies. Unsaturated studies use an air-hammer/under-reamer system that pulls casing down as the hole is drilled. This allows wells and instrumentation to be installed inside the casing before the casing is pulled out of the hole. Reverse air circulation is also a method offered by the WRRDP.

Cores in saturated and unsaturated zones can be taken using the push-core barrel. Two-foot cores can be analyzed for both physical and chemical properties.

The rig's 900 cfm/350 psi air compressor forces the cuttings to the surface through the diverter to the cyclone. The cyclone allows air to escape upwards while cuttings drop out through the bottom. For larger diameter holes, a backup unit can be piggy backed to the rig's compressor for additional air volume.

Drilling site using air-hammer drilling method

Casing jacks"push" casingback out ofhole with 50,000 pounds of force.

8-inch threaded casing(6-inch is also availablefor use with this system)

Air swivel diverter directs cuttings tocyclone

Air hammer

Guide device

Air

Cuttings

Cyclone

Under reamerand pilot bit

Air Drilling

Drill bit

The pickup pump "vacuums" mud and cuttings from the borehole and diverts them to the shaker or mud-filtering system.

The shaker tank serves as the mud filtration system. Once filtered the mud is then pumped back down the borehole.

Typical cuttings collected by sieving mud and/or samplingfrom the shaker screen and cones.

Dual positive displacement (piston) mud pumps force the drilling fluid down the borehole when the rig's centrifugal pump is over pressured.

These pumps are used at deeper depths.

Both Direct and Reverse mud circulation methods are offered by the WRRDP. Direct mud circulation allows the scientist to collect both sieve and shaker samples. Spot coring is also possible. This method allows for rapid drilling of larger diameter holes and reaming of pilot holes. Flooded Reverse circulation uses either mud or water + polymers and air. Samples obtained using this method are very clean and accurate.

The shaker screen separates drilling mud from coarser cuttings.

The desilter cones or desander separate the finer sands from

drilling mud.

Reliable grout seals are set using a high-pressure positive displacement piston grouter.

Mud pumps

Stabilizer

Drill bit

Stabilizer

Drill pipeor collar

Fluid pathFluid path

Mud Drilling

Reverse circulation dual wall pipe

Heat dissipation probes

Wires attached to two advanced tensiometers and seven heat dissipation probes

Instruments are wired to data-logger

0 10 200

300

600

900

1,200

1,500

0 100 200 -50 100 250 0 75 150 0 75 150 0 200 400

Caliper,in

inches

DEP

TH F

ROM

LA

ND

SU

RFA

CE, I

N F

EET

Gamma,in counts

per second

SP,in

millivolts

SpontaneousPotential Resistivity Resistivity

Electro-MagneticInduction

(Conductivity)

16-inch,in ohms

per meter

64-inch,in ohms

per meter

EM,in millimhos

per meter

Geophysical logs and lithologic informationWell site 4S/12W-25G 1-6 (Long Beach water 1)

0 5,000 10,000

Vs and Vpvelocity, infeet per sec

GROUT

GRO

UT

GRO

UT

SAN

DSA

ND

SAN

D

4 3215 6Fill

Silty sand

Silty sandSilty sand withcoarse beds

Silty sand

Silty sand

Silty sand

Sand

Sand

Sand

Sand

Coarse sand

Coarse sand

Sandy siltBedded siltwith sandlayers

Bedded siltwith sandlayers

Sand

Silty muddy sand

LithologyWell

construction

SAND

SCREENEDINTERVAL

0

300

600

900

1,200

1,500

Dep

th fr

om L

and

Surf

ace,

in F

eet

Instrumentation installed in borehole at Artificial Recharge Pond tracks downward migration of recharge through an unsaturated zone.

Well (piezometer)covered by rag

Well construction and instrumentation is performed by the WRRDP. For ground-water studies, typical construction well nests include five to six individual monitoring wells. The screened interval of each well is surrounded by a sand pack. Seals are pressure grouted into place between screened zones.

Installation of unstaturated zone study instrumentation, such as neutron logging access tubes, gas-sampling tubes, psychrometers, temperature probes, and lysimeters, are standard procedure for the WRRDP. Seismometers and strain meters can also be installed for earthquake studies.

Geophysical logging services are included in all holes the WRRDP drills. Logs are printed onsite and digital files can be e-mailed to project managers. Standard logging tools which accompany the van include the following: resistivity tool (16-inch, 64-inch, lateral gamma, SP, temp., fluid resistivity), electromagnetic induction tool (conductivity, gamma, in open or fluid-filled hole), caliper tool, and deviation tool or inclinometer. Special tools can also be also run such as the acoustic televiewer, sonic (density), spectral gamma, and the borehole camera.

Inside of van showing computer used to run logging and plotting software

Geophysical tools used

Drawworks comes with2500 feet of cable

Resistivity

Deviation

ComputerPrinter

Caliper

EMinduction

Borehole Geophysical Logging Well Construction

Logging and Construction

0

50

100

150

200

250

300

350

400O-02 D-02 M-03 J-03 S-03 D-03 M-04 J-04 S-04 D-04 M-05 J-05

Date

Dep

th, i

n fe

et

Position of wetting frontAdvanced tensiometersHeat dissipation probesElectromagnetic logs

Downward movement of wetting front at VVWD recharge pond along Oro Grande Wash near Victorville, southern California

downward rate of movement ~ 0.27ft/d

From J.A. Izbicki San Diego Ca.

EM Logs forWell CM2

mS/m

Feet

Feet

CM2 EM Log1994 & 1996

Change(1994 – 1996)

CM2 EM Log1994 & 1996

Change(1994 – 1996)

100

200

300

400

500

600

700

800-800mS/m 8000

mS/m 800-800mS/m 8000

The EM log conductivitydecreased in well CM2

at 150 to 240 feet belowland surface, indicating

a retreat of theseawater front.

Feet

Feet

100

200

300

400

500

600

700

800

900

Q2 EM Log1994 & 1996

Change(1994 – 1996)

Q2 EM Log1994 & 1996

Change(1994 – 1996)

mS/m0 600 mS/m-600 600

mS/m0 600 mS/m-600 600

EM Logs forWell Q2

The EM log conduc-tivity increased

in well Q2 at800 to 850 feet

below land surface,reflecting continued

water-qualitydegradation in the

lower aquifer systemin this area.

EM data are proven with data from instruments installed in the

borehole.

Changes in EM logs over time show the downward movement of

the wetting front

The WRRDP has experience in monitoring via geophysical logging. Two examples below demonstrate the ability of Electromagnetic Induction logs (EM logs) to track both fresh water recharge through the unsaturated zone in a desert environment and seawater intrusion in coastal environments. Temperature and flow metering are other very useful logs that can be run repeatedly over time.

For more information on this USGS program contact:Steven Crawford (702) 564-4541 or e-mail: smcrawfo@usgs.gov

Monitoring

A comparison of EM logs done in 1994 (red) and 1996 (blue) shows the changes that occurred during the 2-year period.